Rainfall

Following a wet October, Sydney returned to hot, dry conditions during November. Observatory Hill had a total rainfall of only 13.4 mm, which is well below the historical November average of 83.5 mm. It is the driest November at Observatory Hill since 1962 (when 10.4 mm) and ranks as the 18th driest November out of 152 years of record. The rain fell on 8 days, which is below the average of 12 rain days. The entire metropolitan area recorded below average rainfall with many suburbs recording their driest November since 1982. Slightly higher totals occurred in some southern suburbs and on the far northern beaches where thunderstorm activity was greatest. Monthly totals in metropolitan Sydney ranged from 35.0 mm at Peakhurst in southwest Sydney to only 6.8 mm at Collaroy on the northern beaches. A thunderstorm on the 20th produced 14 mm at Avalon, the highest daily rainfall in the metropolitan area during November.

A very slow moving high pressure system in the Tasman Sea for much of the month provided stable conditions along the central and southern coast with little rainfall in the Sydney region. The few low pressure troughs that managed to cross the region were very weak and produced little or no rainfall over the city.

Dry conditions also prevailed over the Warragamba Dam catchment with most falls between 10 and 40 mm for the month. The dry weather caused Sydney's storage level to fall by 2% during November and is currently around 55% of capacity. Recent rainfall and current levels in Sydney's water catchments can be found on the Sydney Catchment Authority web site http://www.sca.nsw.gov.au/dams/rainfall.html

Temperatures

Sydney has recorded its hottest November on record. The average mean temperature (average of maximum and minimum) was 22.4 ° which is 2.8 °C above the historic mean average. The previous hottest November was in 1914 with a mean temperature of 22.0 °C.

Daytime temperatures were well above average with long spells of warm, sunny days and the occasional hot day, especially towards the end of the month. Sydney Observatory Hill recorded its 2nd highest November temperature on record, 40.4 °C on the 22nd. Observatory Hill recorded an average monthly maximum temperature of 26.1 °C, which is 2.5 °C above the historical November average. This is Sydney's highest November average maximum temperature since 1897 (when 26.4 °C). Sydney's hottest November with respect to average maximum temperatures was in 1894 (26.5 °C). It was several degrees hotter in Sydney's western suburbs with an average maximum of 32.2 °C at Penrith, at least 4 °C above the historic average.

Sydney Observatory Hill recorded 6 hot days (temperature over 30 °C) during November, the highest number since 7 days in November 1966. It was even hotter in Sydney's western suburbs where the cooling sea breeze failed to penetrate. The November total of 17 hot days (temperature over 30 °C) at Richmond was the highest since 1957 and 20 hot days at Penrith (highest on record).

Very warm nights were also experienced throughout the metropolitan area during the month with Sydney Observatory Hill recording its highest average minimum temperature on record for November. The average minimum of 18.7 °C was a significant 3.1 °C above the historic average. The previous highest was 18.5 °C in 1914. Numerous other locations around the metropolitan area also recorded their highest average minimum temperature on record for November. Warm nights were common during November with 21nights having a minimum greater than 18 °C, easily exceeding the previous highest number of 18 nights set in 1914. The normal frequency for November is 5 nights above 18 °C. There was also a record total of 6 very warm nights (minimum greater than 21 °C), double the previous highest frequency of 3 nights set in 1984 and 1914. This compares to Sydney's normal frequency of one very warm night in November every 3 years.

The high temperatures in Sydney were mainly due to slow moving high pressure systems that remained almost stationary in the Tasman Sea for much of the month. The trailing edge of the highs directed warm to hot northerly winds over the state and in the Sydney area for most of November. The heat peaked on the 22nd with temperatures in metropolitan Sydney exceeding 40 °C.

An El Niño event is currently maturing in the equatorial Pacific Ocean. These events are usually (but not always) associated with above average temperatures in eastern Australia. Very high temperatures experienced throughout winter and spring are likely due to the current influence of El Niño combined with the background, long-term warming that has been observed across Australia since the start of last century.

There was significant variation in temperatures over the Sydney region during November, with extremes ranging from a high of 42.5 °C at Sydney Airport on the 22nd to a low of 8.9 °C at Camden Airport AWS on the 14th. The warmest night was 23.1 °C at Penrith on the 21st.

Wind

Coastal Sydney experienced prevailing E-NE winds during November, with a frequency of 63% from this direction at 3pm compared to the historic average of 47% from this direction. However, the winds indicated a more northerly component in the western suburbs with a frequency of 48% from the NE-NW at Richmond. The highest wind gust was 94 km/h at Penrith Lakes AWS on the 20th during a thunderstorm.

Other phenomena

Observatory Hill recorded 4 thunderstorms during the month, on the 12th, 16th, 20th and 23rd but were accompanied by little or no rainfall. The most severe was on the 20th when 2 houses caught fire after being hit by lightning and a localised downburst in the Church Point area (northern suburbs) caused extensive damage to houses and brought down trees. Raised dust with westerly winds on the 29th reduced visibility to 5 km over Sydney. Sunshine averaged 7.8 hours per day, slightly above the November historical average of 7.6 hours per day.

Daily rainfall

Most values are the precipitation in the 24 hours to 9 am on the day indicated.
Days marked with »» are part of a longer accumulation, which is marked like this on the final day.
Values over 100 mm have been rounded to the nearest whole millimetre.
Days marked with - have a rainfall report of zero;
days left blank have no rainfall report (which often indicates no rain fell).
This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.

Notes

A Monthly Climate Summary is prepared to list the main features of the weather in Sydney - Greater Sydney using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at
10 am on Tuesday 1 December 2009.
Some checks have been made on the data, but it is possible that results will change
as new information becomes available.

Averages are long-term means based on observations from
all available years of record, which vary widely from site to site.
They are not shown for sites with less than 20 years of record, as they cannot then be calculated reliably.
The median
is sometimes more representative than the
mean
of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site,
based on the
decile ranking
(very low rainfall is in decile 1, low in decile 2 or 3,
average in decile 4 to 7, high in decile 8 or 9
and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a
percentage of the long-term mean.